Technical Description of OBD-II Trouble Code
The Cruise Control Multi-Function Input B Circuit is Stuck
What does that signify?
This is a standard powertrain diagnostic trouble code (DTC) that is commonly found in OBD-II vehicles. This code can apply to various vehicle brands such as Mazda, Alfa Romeo, Ford, Land Rover, Jeep, Dodge, Chrysler, Chevy, Nissan, and more. While it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
Cruise control was designed to enhance our driving comfort. Its main purpose is to maintain a manually set vehicle speed, which can be done through various controls such as steering wheel buttons or a multifunction switch mounted on the steering column.
With cruise control, the driver no longer needs to control the gas pedal, and in vehicles with automatic transmissions, it can also adjust shift points based on real-time driving conditions.
In this case, it is likely that the multifunction switch on the steering column is the source of the issue. However, the exact location may vary depending on the manufacturer. Start by checking the cruise control button to narrow down the possible locations. This code refers to a specific input circuit within the cruise control system. To determine which wire or circuit to focus on, consult the service manual and use the letters in the codes as a reference.
When there is a fault in the cruise control multi-function “B” input circuit, the engine control module (ECM) will illuminate the instrument cluster with the P0590 code and related codes (P0589, P0591, P0592, and P0593).
The letter “B” in this context could be used to distinguish a connector, wire, or circuit group. The manufacturer’s specifications will provide the best information for this.
P0590 is set by the ECM when the “B” cruise control multi-function input is electronically or possibly mechanically “stuck”.
A cruise control stalk:
What is the severity of this DTC?
This DTC is generally considered to have low severity, although there may be exceptions. In most cases, this fault should not cause serious concern. However, electrical issues tend to worsen over time. The cost of fixing this fault is usually moderate. It is important to shop around for the best prices and obtain multiple quotes and diagnosing strategies. Additionally, staying on top of general vehicle maintenance is always recommended.
What are some of the symptoms of the code?
Symptoms of a P0590 trouble code may include:
What are some of the common causes of the code?
Causes for this P0590 code may include:
What are some P0590 troubleshooting steps?
Basic Step #1
Once you locate your vehicle’s multi-function/cruise control switch, visually inspect it for any contamination. Plastic buttons/switches can easily become dirty, greasy, or sticky, leading to malfunctions or abnormal operation. Ensure that the switch operates smoothly. Address any problems immediately. If your scan tool or OBD reader allows it, observe the electronic operation of the switch through DATA STREAM or a similar mode that provides real-time data.
TIP: Avoid spraying cleaning solutions directly onto the button. Instead, lightly dampen a clean rag with water, soap and water, or dash cleaner, and carefully remove debris from the switch’s crevices. An air-powered blow gun can help remove debris without worsening the situation.
Basic Step #2
To access the connectors and harnesses involved in the cruise control/multi-function switch input circuit, you may need to remove some dash plastic or shrouds. Be careful when working with plastic. Comfortable room temperatures can make dash/interior plastic disassembly/assembly easier.
If you can easily access the connector, you may be able to follow specific troubleshooting steps provided by your service manual. Switch testing will likely involve recording electrical values using a multimeter. This may include operating the switch while recording or performing static testing. Consult the specific make and model’s service manual for a diagnostic flow chart.
Basic Step #3
A problem within the ECM is usually the last resort in diagnosis. Given that it can be one of the most expensive electronic repairs for a vehicle, it is best to leave this to the professionals.
